Be Kind to your Grass this Winter

At this time of year we are subject to heavy frosts in unusual places.  If the temperature is below freezing, there is a good chance frost will be present somewhere.  Do not drive, walk or work on the grass when temperatures are below freezing!  And here’s why:

Grass blades are exquisitely beautiful when covered with frost.  There is something magical about a hoary frost in the early morning light which conjures picturesque images of Jack Frost and the winter to come.  However, do not be fooled by the fairy tale. Far from benign, frost is essentially miniature frozen daggers arranged randomly all over the turfgrass blades.  When you walk or drive on frosted grass, the pressure of your foot or tire forces these tiny ice daggers into the grass blade.  Nobody wants to get stabbed by millions of tiny ice daggers, least of all turfgrass blades.  When this injury happens, the grass blades first turn black, then brown as they die a tortuous death.  Additionally, turf damage done at this time of year is particularly devastating because the grass blades have stopped growing for the season.  Turfgrass damaged in the fall or winter will not recover until next spring.  Any damage that occurs now will be a constant reminder throughout the entire winter of your senseless disregard for the health and well-being of turfgrasses everywhere.

The tricky thing, however, is that just because there is no frost visible does not mean there is no frost present.  A light frost or a frost at soil level will not necessarily show itself.  Sometimes, even a heavy frost will melt off the outer turfgrass canopy but still be present on the interior canopy long after air temperatures have risen above freezing.

So, in the humble opinion of an expert horticulturalist, your best course of action is as follows:

1) Never drive on the grass in the winter.
2) Never walk on frosted grass.
3) Stay on the paved paths.

For the sake of your turf, it is better to enjoy the frosted beauty of winter from your cozy chair by the window, as you sip your cocoa, pour over garden catalogs and dream of mows to come.

Morris Arboretum’s Executive Director Wins Prestigious National Award

AHS Award (left to right) Jane Diamantis, Chair of AHS Great American Gardeners Awards Committee; Paul Meyer; and Tom Underwood, AHS Executive Director

Paul W. Meyer, the F. Otto Haas Executive Director of the Morris Arboretum, received the prestigious Liberty Hyde Bailey Award from the American Horticultural Society (AHS) at its June 5th Great American Gardeners Awards Ceremony at River Farm in Alexandria, Virginia. AHS presents the Liberty Hyde Bailey Award to an individual who has made significant lifetime contributions to a least three of the following horticultural fields: teaching, research, communications, plant exploration, administration, art, business, and leadership.

“There is little doubt that Liberty Hyde Bailey was the most important proponent of Horticulture in America during the late 19th and early 20th centuries. It is more than fitting that this award goes to Paul Meyer for his achievements in administration, communication, institution-building and plant introduction.  His career has epitomized the breadth and magnitude of accomplishment for which this award was created.  Throughout his career Paul has never sought personal acclaim for his accomplishments, but has exerted servant leadership as primus inter pars - first among equals.  By embodying that rare quality of close identification with the institution he has served for almost four decades, Paul has created something more lasting and more positively effective than any personal fame.  I am pleased to have known him over his entire career, and to be able to say that this man is my friend,” said Dick Lighty about Meyer’s award. Lighty himself was a recipient of the award in 1999.

“This recognition would not be possible without the help of a dedicated Board, hardworking staff and volunteers, and all of the Arboretum’s generous supporters. “Meyer was quick to add when congratulated for this prestigious award. “This is an affirmation of the national and international impact of the Morris Arboretum”, he continued.

Paul W. Meyer has been the F. Otto Haas Executive Director of the Morris Arboretum of the University of Pennsylvania since 1991. Meyer came to the Arboretum as curator of the living collection in 1976, and has played a significant role in its transformation from a dilapidated lesser-known former private estate into a world-class public garden that welcomes approximately 130,000 visitors each year.

The Morris Arboretum is also a research and educational institution that maintains a database of Flora of Pennsylvania and participates in international plant exploration expeditions. Meyer helped found the NACPEC (North America-China Plant Exploration Consortium) in 1991 and has traveled extensively to China and other parts of the world in search of new plants to evaluate for introduction to American gardens. Through the NACPEC, the Morris Arboretum and other prominent participating North American public gardens have developed a strong relationship with Chinese botanical gardens to share information aimed at improving plant conservation efforts and widening the generic pool of species commonly used in horticultural breeding programs.

Just as the Morris Arboretum has become more widely recognized in recent years, Paul Meyer is not just Philadelphia’s secret. With this award and many others from horticultural organizations, he is clearly recognized for his achievements, and well respected among his peers nationally.

Katy Moss Warner, President Emeritus of the American Horticultural Society and currently Vice President and City Judge, America in Bloom commented that, “ Paul speaks often about "standing on the shoulders of giants" in order to have experienced and achieved what he has in this world. He is certainly passing it on. His tall shoulders have inspired many in America and around the world.

The American Horticultural Society couldn't be prouder as we recognize Paul Meyer as the 2014 Liberty Hyde Bailey award winner and add him to the list of those we consider the finest and most influential horticulturists in America.”

Winter Weeding: Hairy Bittercress

Cardamine hirsuta
Hairy Bittercress
By Emma Erler, The Alice and J. Liddon Pennock, Jr. Endowed Horticulture Intern

This time of year there isn’t too much happening in the garden. Most plants have gone dormant for the winter. However, as the snow melts you may notice a low growing plant with a basal rosette of leaves. This is a common weed in the mustard family called hairy bittercress (Cardamine hirsuta).  Hairy bittercress is a winter annual, which means its seeds usually germinate in cool, moist weather. Seedlings emerge mainly in late summer or fall. They are frost hardy and will remain dormant through the winter until temperatures warm up. In early to mid-spring, hairy bittercress will resume growth, produce flowers, and go to seed. Plants die back as soon as hot weather arrives in late spring and summer.
As a seedling, hairy bittercress has simple kidney-shaped leaves. Mature plants have prominent basal rosettes of hairy, compound leaves with shallowly lobed kidney-shaped leaflets. Flowering stems emerge from the rosette and have only a few small leaves. Hairy bittercress flowers are very small (2-3 mm) in diameter with four white petals. The subsequent fruits are 1-2 cm long capsules that explosively disperse their seeds up to 3 meters from the plant.

The best way to control hairy bittercress in the garden is to remove it before it sets seed. Each plant is capable of producing many thousands of seeds, hence removing the plants before seeds are set will greatly control the population. Small populations can be easily hand pulled from the garden. In large areas, regular hoeing will prevent plants from flowering and going to seed.
 For the adventurous gardener, hairy bittercress is an edible green. Tender leaves collected in early spring or late fall can add a peppery taste to salads.

As the winter progresses, keep an eye out for hairy bittercress and get ready to weed as the weather warms up!

Photos: Emma Erler

Counting the Birds: A Christmas Tradition

From December through January tens of thousands of volunteers throughout the Americas take part in an annual mission: The Christmas Bird Count. For over one hundred years, the desire to both make a difference and to experience the beauty of nature has driven dedicated families and students, birders and scientists to brave the winter weather, armed with binoculars, bird guides and checklists , to count the birds!

Each of these citizen scientists make an enormous contribution to conservation. Audubon and other organizations use data collected in this longest-running wildlife census to assess the health of bird populations - and to help guide conservation action.

On December 21, 2013 several Morris Arboretum staff members participated in this annual tradition. Of the birds sighted, some of the most notable were:  

• A flock of 220 Snow Geese
• Cormorants, Mallards, and Wood Ducks
• Wood Thrush
• Brown Creepers
• Carolina wren
• Red-tailed hawk
• White-throated sparrow
• Yellow-bellied Sapsucker

And perhaps the most exciting sighting: A pair of Bald Eagles spotted at Bloomfield Farm!

Pictured left to right: Carolina Wren, Red-tailed Hawk, White-throated Sparrow (Photos by Susan Marshall).

Visit the National Audubon website for more information about the census and how you can participate in 2014.